1. Field of the Invention
The present invention relates to an ink jet recording apparatus which is capable of recording images on a recording medium by discharging a recording liquid, and an ink jet cartridge which can be mounted on such an ink jet recording apparatus.
2. Description of the Related Art
In a liquid jet recording apparatus having an exchangeable liquid injecting/recording head, the recording head must be positioned precisely so as to allow the accuracy with which a recording liquid can be discharged at a required position on a recording material to be improved or so as to allow the recording head to be electrically connected to an apparatus body. Conventional methods of, or devices for, positioning a recording head have been proposed in the specification of, for example, U.S. Pat. No. 4,692,778. In this method, a platen for retaining a recording material is provided with a recording head positioning portion. The recording head is supported at least three points while being fixed by an elastic member.
U.S. Pat. No. 4,628,332 proposes a structure in which an elastic member is provided on the inner side of a mounting member for detachably retaining a recording head, by means of which the recording head is fixed to the mounting member. This elastic member has a convex portion for pressing the upper portion of the mounted recording head to fix the recording head firmly.
Various structures for positioning a recording head relative to a carriage for retaining the recording head have also been developed. FIG. 1 shows one example of such a recording head positioning means. In this structure, exposed surfaces of supporting plates constituting the recording heads are brought into contact with contacting surfaces of a carriage so as to allow individual recording heads to be disposed on the carriage at a predetermined interval. The side surfaces of the supporting plates of the individual recording heads are pressed by spring members 1111a, 1111b, 1111c, and 1111d such that the supporting plates are reliably in contact with the contacting surfaces of the carriage 1110. The carriage 1110 is moved along a scanning rail or sliding rail 1112.
U.S. Pat. No. 4,633,274 discloses a recording head positioning structure in which electrode pins provided on the recording head and serving as positioning pins are inserted into connector sockets of the supporting member for supporting the recording head, by means of which an electrical connection with and positioning of the recording head relative to the supporting member are achieved.
Structures for achieving both positioning of a recording head relative to a recording head retaining carriage and an electrical connection between the recording head and an apparatus body have also been developed. FIG. 2 shows an example of such a structure. In this structure, a recording head 1201 and a separately formed connector 1261 are connected with each other by a flexible cable 1260. In consequence, an operation for connecting the connector 1261 provided on the distal end of the flexible cable 1260 to a connector 1262 provided on an apparatus body is required, in addition to an operation for positioning the recording head 1201. A carriage 1202 is moved along a scanning rail 1211 and a sliding rail 1212. The recording head has an ink tank 1213. A reference numeral 1263 denotes a printed circuit board.
Thus, various types of recording head positioning structures have been proposed heretofore. However, in the aforementioned structure, for example, in which a recording head and a connector are formed separately, when the recording head is to be mounted on or removed from the carriage, two operations are required: an operation of mounting the recording head on or removing it from the apparatus body, and an operation of connecting the connector provided on the head to or disconnecting it from the connector provided on the apparatus body. This is very inconvenient for users. In particular, mounting a plurality of recording heads may cause connector connection errors.
Furthermore, in a recording apparatus in which a plurality of recording heads are disposed on a carriage at a predetermined interval for recording, as in the case of the apparatus shown in FIG. 1, in a case where a full color image is recorded by moving the carriage 1110 at a fixed speed, the individual recording heads must be positioned with a high degree of accuracy so as to form an excellent image.
More specifically, the droplets having different colors and discharged from the corresponding recording heads CA, CB, CC, and CD in accordance with recording signals must be deposited on the recording material at the appropriate positions with great precision.
This is necessary, because, if the points on the recording material on which the droplets of different colors impinge shift from their predetermined positions by a certain distance (e.g., about 0.03 mm) or above, visually recognizable color defects may occur in the image formed, causing so-called printing failure and making the recording apparatus an inappropriate one which cannot fulfill the requirements of the recording apparatus.